Two-temperature refrigerating apparatus



S. M. SCHWELLER TWO-TEMPERATURE REFRIGERATING APPARATUS March 16, 1954 5 Sheets-Sheet l Filed April 28, 1951 1N V EN TOR.

` Sylyeser M. Schweller Fly.

BY @QM l y,

Attorneys March 16, 1954 s. M. scHwELLER y TWO-TEMPERATURE REFRIGERATING APPARATUS Filed April 28, 1951 5 Sheets-Sheet 2 //N/V/// /M 0// /f/V/M/ H/// l///// l/ /f O Fig. Y2y

INVENTOR. Syl vesfer M. Schweller Attorneys 5 Sheets-Sheet 3 Marh 16, 1954 s.I M. scHwELLER TWO-TEMPERATURE REFRIGERATING APPARATUS Filed April 28, 1951 s. M. scHwl-:LLER 2,672,025

TWO-TEMPERATURE REFRIGERATING APPARATUS 5 Sheets-Sheet 4 Attorneys March 16, 1954 File-d April 28, 1951 March 16, 1954 s, M SCHWELLER 2,672,025

TWO-TEMPERATURE REFRIGERATING APPARATUS Fled April 28, 1951 5 Sheets-Sheecl 5 FIG. 5

Patented Mar. 16, 1954 TWO-TEMPERATURE REFRIGERATING APPARATUS Sylvester M. Schweller, Oakwood, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application April 28, 1951, Serial No. 223,590

Claims.

This invention relates to refrigerating apparatus.

An object of this invention is to provide an improved mechanical refrigerator which is adapted to be manufactured in large quantities and be distributed and used throughout the United States. This refrigerator is refrigerated by a simple compressor, condenser, evaporator system having no controls other than the usual refrigerantY expansion and compressor cycling controls.

The refrigerator has a -cabinet with an outer wall substantially hermetically sealed against breathing action with the outside atmosphere. An inner liner is placed inside the outer casing and closely follows its contour, with the neces- `sary insulating space between the casing and liner. The liner is so constructed or is provided With an access from the interior of the liner to the insulation space, so that breathing action can take place between the insulation space and the interior of the liner. Insulation is placed in the interior of the insulation space in the form of hermetically sealed bags containing insulation, which bags are made of some impervious material such as polyethylene.

A frozen food compartment is provided in the upper part of the refrigerator. It is maintained at very low temperature and is of rectangular cross section adapted to receive rectangular food packages, to be fully packed with them, and to prevent local warm spots among such frozen food packages. This frozen food compartment, with its surrounding insulation, is placed inside of the liner, so that its inner surface is at a very low temperature, and the outer surface of the insulation is above 32 F., so that no frost can gather on the outer surface of the insulation.

The refrigerator is also provided With an unfrozen food compartment to be maintained at a low temperature, above 32 F., which compartment is adapted to receive foods in large quantities which are to be maintained above 32 F. and which are not likely to be dehydrated. This unfrozen food compartment is also provided with one or more covered pans having a space in which relatively high humidities are maintained and in which foods may be preserved which are likely to be otherwise dehydrated.

Notwithstanding these advantages, the refrigerator is adaptedto operate satisfactorily 'in varying atmospheric temperatures ranging from 50 to as high as 110. It is also adapted to operateV satisfactorily in varying degrees of atmospheric humidity, Vfrequently reaching substantially the saturation point of relative humidity, without danger of accumulating undesirable moisture within the compartments or Within the insulation surrounding the compartments. y

The cabinet is provided with an outer door eX- tending throughout the edge of the outer casing, and engages the outer casing with a sealed construction in a manner to reduce infiltration of outside air into the refrigerator.

The frozen food compartment preferably is made of a rectangular sided compartment virtually surrounded on all sides, except the door side, with a freezing evaporator placed on the outside of the frozen food compartment liner, which liner is made smooth on the inside to receive frozen food packages and to be easily scraped of a slight amount of frost which may gather after long periods of use. The compartment is adapted to be maintained cold Without defrosting for relatively long periods of time (several months). Insulation is placed around the frozen food compartment, and is made suiiiciently thick to cause the outer surface of the insulation to remain above 32 F., within the cabinet liner. The insulation is hermetically sealed against any breathing action which would permit any substantial accumulation of frost adjacent the freezing evaporator, on the outside of the frozen food compartment liner. This insulation may be made of hermetically sealed bags with surface so closely pressed against the outer surface of the frozen food compartment liner, that only a slight amount of frost can ever gather adjacent the freezing evaporator, or the insulation can be so hermetically sealed that no accumulation at all can occur Within the insulation. The frozen food compartment, with the freezing evaporator and the insulation is adapted to be inserted into the upper part of the unfrozen food compartment liner.

The unfrozen food compartment is formed by that portion of the cabinet liner Which extends below the froaen food compartment. The space between the cabinet liner and the outer casing is insulated by surrounding the liner with bags of insulation (hermetically sealed bags of polyethylene enclosing glass or mineral wool) pressed against the outer surface of the liner, so that no moisture Whatever can gather inside the bags, and substantially no moisture can gather on the outer walls of the liner and nowhere insidethe bags. In order to cool the major portion of the unfrozen food compartment, and in order to pre- Vent accumulation of moisture either inside of and the outer casing, and hence continuously i freezes moisture from these places and prevents any material accumulation of moisture within the cabinet.

A motor compressor unit and condenser are placed in the lower part of the refrigerator and fare :in rrefrigerant, flow relationship with the freezing'. evaporator and thefrostingy and defrostiingfaevaporator. The compressor'is cycled fre- .qnently:(severaltimes aday) to maintain the desired temperature conditions in the refrigerator and this is 'accenfiplished by*` providing a thermostatic switch having. its thermostatic bulb in sub- ;stantial .contact withfthefrosting and defrost-ing fevaporator. The switch:starts the compressor when the frosting and .defrosting evaporator reachesfa temperature above 32F. suchl as 34 F. .and after this levaporator rhasvdefrosted, and causes-fthe compressor to run until this evaporator reaches a veryY low frosting temperature, lower than the temperature of. thefrozen food col- A partmentfsuchas 0' F.

The:constructionaandfrelationshipof the freezing evaporator'and the 'frosting Aand ydefrosting evaporator aresuch that.. alarge portion of liquidrefrigerant'rin the frostingxand defrosting fevaporator isA forced, in `liquid form, into the .freezing-evaporator duringv'the defrosting cycle, .thus reducing the amountf-ofheat and length `of Atime-required tof defrostrthe: frosting and: defrostiingfevaporator.

"This refrigerator is adapted-to maintain .the lfrnzen..food :compartment .uninterruptedly below 32 *without ,the defrosting for long :periods of V`time, :such as. several months; 4independently tof .,thefcycling-of the motor 'compressor Junit, which -cyeling occurs several times raday,v since theA tem.- zperature of'th'eliquid'refrigerant inthe freezing'evaporatordo'es not rise yabove 32 even 'duringtheldefrosting periods. The refrigerator 4isrmaintained inpropertcondition by the 4auto- .matic Vdefrosting the A'frosting and defrosting A evaporator, which operation is performed: during f-ea'ch fcompressorl'cycle and so `qnicklythat no .fmeltingfcan take :place in thefrozen 'food com- `pa-rtment. The refrigerator-:canoperate at very 4 ture refrigerator embodying one form of my invention;

Fig. 2 is a vertical sectional View taken substantially along the line 2-2 of Fig. 3 with the side insulation removed of the bottoni portion of the two temperature refrigerator, the upper por- "tion ofwhiclil is `shown inf'Eig.. l

Fig.. 3 is; afragmentary front vertical sectional View taken substantially along the line :4*3 of Figs 1 and 2;

Fig. 4. is a fragmentary rear vertical sectional .vien/'taken'substantially along the line dof Figs. l and 2 with the back insulation removed;

Figf .is'aperspective view of the removable twounit primaryrefrigerant evaporating circuit Fig. 6.is. a side view of the removable two unit refrigerant evaporating system;

Fig. '7 is a front view of the removable two unit refrigerant evaporating system with the door closed;

Fig. 8 is a vertical sectional view of a modied form 'of freezing compartment -container ;v and Figfg isafragrnentary enlarged portionY of the 'lower front edge ofFig. 8vshowingthe method of sealing.

Referring now to thedrawings there is provided anfouter hermetically sealed sheet metal cabinet'sheil 23 enclosing-the top 22, bottom 24, 2i?Y and 222.,V and rear 30of the cabinet. The joints of this shell are sealed by weldingv or other suitable metal seal and preferably "are addiztionally sealed onl the interior'by theuse of some form of non-metallic 'sealing material such as `asphalt applied in molten form.

vmetal-:outer doordcontaining insulation. It is .provided wtih. a gasket type seal 43 extending entirely around the door-.which makes-.sealing engagement with the'front vt5`Y of the outer shell 20. IFhisseals the-interior'of the cabinet from the outside-air. Because'ofthis completely hermetical'sealing of the outside of thel cabinet'no airor moisturercan enter the cabinet exceptfby opening the door 46.

The-cabinet is provided with a completely revmovable series type two unit primary `evalporating vsystem including an insulated, completely Aenclosed freezing compartmentcontainer 32 and a vertical.refrigerant'plate S0 fastened to the bottom Aof the container 32; Referring .now more particularly to Figs'. l to J4 inclusive, the `freezing compartment container-32 isiformed of'an inner .box-shaped'metal can 220. Bonded'to the outer surfaceof this can 225i is'a tubular'series type refrigerantevaporator including aserpentine portion 222provided on the right side, a second serpentine portion 224 provided on the top, a third serpentine portion 226 providedon the left side. land a vserpentine portion v2223 provided upon the bottom. The configuration of this primary freezing evaporator, composed of rthe'serpentine portions-222 to 228, is shown'in Fig. 5. The bottom serpentine portion228 connects onto the bottom :of alcylindrical tank 23B which serves as a disengaging tank and accumulator.

Insulating means 22 I, such as glass or mineral .wool,ris provided upon-all, sides ofthecan 22B-and -the freezing evaporator coils. "is'then enclosed in an outer box-shaped metal front edge of the outer can 232.

The insulation 22| can232. The gap betweenthe front edges of the inner and outer cans 2201and 232 is sealed by vsome suitable thermoplastic sealing material 234,

such as hot asphalt. The front edges are structurally connected by a thermoplastic member 235 yof polystyrene or phenol formaldehyde resin which provides a structural connection between the cans which also serves as a heat transfer barrier. By this arrangement, the space between the cans 220rand 232 is hermetically sealed.

The interior of the can 220 is closed by an inner .convenient compartment for frozen foods which are normally vpacked in box-shaped containers. 'Because of the double can construction with the insulation and the serpentine evaporating portions directly in Contact with the inner can, this unit'has a relatively high mass and holdover capacity. This insulation between the inner can 220 and the outer can 232 is suicient so that even though the inner can and its interior should be cooled below F., the outer walls thereof will always remain above 32oA The outer can 232 -is so shaped that it exactly fits within the'top part of the inner liner 38 and is removably fas'- tened therein by any suitable means.

For cooling the remainder of the space within the liner 38 below the freezing compartment container 32, there is provided a vertical refrigerated plate 99 having a Very small mass and holdover vcapacity relative to its surface area. This plate 90 is provided with a serpentine refrigerant passage I25, the lower end of which is connected by the tubing 94 which connects to the top of the vtank 230 froml which it is fed with refrigerant.

The upper end of the serpentine passage |25 connects with a lower disengaging chamber 244 provided'in the plate 90 which connects by four vertical passages 246 with atop disengaging chamber 248. The upper portion of the disengaging chamber 248 is connected by the suction conduit 250 with the inlet of the motor compressor unit 50 provided beneath theY bottom wall 24. The motor compressor unit 50 withdraws evaporated refrigerant from the accumulator'ZlB and forwards vcompressed refrigerant to the condenser 52 from which liquid refrigerant is conducted through a capillary tube expansion device 54 to the lower inlet portion of the serpentine evaporator section 222 on the right side wall of the can 220. Y The refrigerated plate 90 is supported directly from the outer can 232 by a pair of metal strips '252. The liquidV line 54 and the suction line 250 are placed within the insulation space directly beneath the breaker strip 40 so that by removing the strip 40, the entire primary refrigerating system can be readily removed from the cabinet. AThe operation of the refrigerating system is controlled by a therinostatic control switch 80 which is dis'closedin diagrammatic form.A Pref-` erably it is of the constant'out ontype. It may be constructed in a manner similar to that shown infthe lGrooms Patent No. 2,351,038. It includes contacts 83 which are connected in series with one ofthe supply conductors 84' which'conducts electrical energy to the motor compressor unit 50. It has a temperature sensitive element in the form of a capillary tube 84 which ends in a serpentine portion 86 clamped to the back side of the refrigerated plate 90 as shown in Figs. 3 and 4. This thermostat is set so that its contacts close when the refrigerated plate 00 reaches a temperature of 34 to 36 F. It is set to open at about 0 F. The switch preferably is a fixed cut on type (i. e. fixed closing temperature) but the cut off may be made variable so that the cut off point may vary between about 0 F. and minus 10 F.

The motor compressor unit 50 is of the so called Vhigh side type with the suction line 250 entering pressor of this type is shown in the Rataiczak Patent No. 2,377,965 issued June 12, 1945. With such a compressor properly charged with lubricant and refrigerant, the refrigerated plate will completely defrost during every idle period of the motor compressor unit and will frost during each running cycle to keep the humidity within the unfrozen food compartment space below the freezing compartment container 32 at a desired figure. It will also keep the unfrozen food compartment at an almost constant temperature of about 36 F. regardless of the environment temperature. It will also keep the freezing compartment at a temperature below 10 F. despite the defrosting of the refrigerated plate 9S. The high holdover capacity of the freezing compartment container prevents any large rise in its temperature during the defrosting of the plate 90.

To adjust the system to provide the propel' relationship of the temperatures maintained in the freezing compartment and in the food compartment, the system is placed in a room and after reaching uniform conditions, the thermostat out off is adjusted to a point to obtain the desired temperature in the freezing compartment 32. 1n general, the out off point may be adjusted between minus 5 and plus 5 F.

to obtain a package temperature below 10 F. The refrigerator is then placed in a '70 room and operated until it reaches substantially uniform conditions. The refrigerant charge in the system is then reduced until the refrigerated plate 90 does not receive liquid refrigerant during the initial portion of the running cycle. lf the food compartment 3S is still too cold, additional refrigerant is removed from the refrigerant circuit until the desired food compartment temperatures are obtained. This system provides satisfactory refrigerating temperatures in both the freezing compartment 32 and the food compartment 33 under temperatures varying from '70 to 110.

The bottom of the liner 3B is provided with two covered pans i2? and i2@ which are conveniently arranged to pull out as drawers. Since these pans are substantially closed, it is necessary to provide additional cooling in this area so that the food in these pans are kept at a suitable refrigerant temperature For this purpose there is wrapped about the sides'and back of this compartment, in serpentine fashion, the tubing 13R which'constitutes the evaporator'of food compartment evaporating means being located inside of said liner within the food compartment, a secondary refrigerant circuit having an evapo-rating portion located outside of and in contact with the outer wall surface cf said liner and having a condensing portion inside said liner in direct contact with said food compartment evaporating means with a refrigerant connection between said evaporating and condensing portions, an open substantially unrestricted connection connecting the outlet of said freezing evaporating means and the inlet of said food compartment evaporating means, and a thermostatic cycling control means having a thermally sensitive element in direct contact with said food compartment evaporating means having means for preventing the starting of said liquefying means until the food compartment evaporating means reaches a temperature above 32 F. for defrosting said food compartment evaporating means and having means for preventing the stopping of said liquefying means until said food compartment evaporating means is cooled below said predetermined sub-freezing temperature.

3. Refrigerating apparatus including a hermetically sealed outer shell, a liner within and spaced from said outer shell a distance suicient to provide adequate insulation space, Said liner containing a unitary evaporator structure including an insulated box shaped freezing evaporator and an exposed refrigerated plate connected to and extending from said freezing evaporator, said freezing evaporator including box shaped metal refrigerated walls enclosing a frozen storage compartment and insulating means surrounding said metal walls and a moisture impervious enclosure immediately surrounding s-aid insulating means and sealed to the open portion of said freezing evaporator, said enclosure being of such size and shape to t within said liner, a refrigerant liquefying means having its liquid supply line connected to the inlet of said freezing evaporator and having its suction line connected to the outlet of said refrigerated plate, the outlet of said freezing evaporator being connected to the inlet of said plate and a secondary refrigerant circuit having an evaporating portion located in said insulation space in contact with the outer surface of said liner and having a condensing portion Within the space enclosed by the liner in contact with said plate.

4. Refrigerating apparatus including a hermetically sealed outer shell, a liner Within and spaced from said outer shell a distance sufficient to provide adequate insulation space, said liner containing a unitary evaporator structure including an insulated boi-r shaped freezing evaporator and an exposed refrigerated plate connected to and extending from said freezing evaporator, said freezing evaporator including box shaped metal refrigerated walls enclosing a frozen storage compartment and insulating means surrounding said metal Walls and a moisture impervious enclosure immediately surrounding said insulating means and sealed to the open portion of said freezing evaporator, said enclosure being of such size and shape to t within said liner, a refrigerant liquefying means having its liquid supply line connected to the inlet of said freezing evaporator and having its suction line connected to the outlet of said refrigerated plate, the outlet of said freezing evaporator being connected to the inlet of said-plate and a secondary refrigerant circuit having an evaporating portion located in said insulation space in contact with the outer surface of said liner and having a condensing portion Within the space enclosed by the liner in contact with Said plate, and a thermostatic switch controlling the cycling of said liquefying means and having a thermosensitive element in contact with said plate having means for preventing the starting of said liquefying means until said thermosensitive element rises above 32 F. and having means for preventing the stopping of said liquefying means until said thermosensitive element reaches a temperature below the temperature of said freezing evaporator.

5. Refrigerating apparatus including an above freezing food compartment and a below freezing compartment to be maintained below a predetermined sub-freezing temperature, a thermal heat transfer barrier between said compartments, a common access door for said compartments, a refrigerant liquefying means, a primary freezing evaporating means in heat exchange relation with said below freezing compartment and vhaving its inlet connected to said liquefying means and having its outlet extending above a major portion of the evaporating space to prevent the gravity drainage of liquid refrigerant therefrom, a food compartment primary evaporating means in heat exchange relation with said food compartment, a liner surrounding the food compartment, said food compartment evaporating means being located inside of said liner within the food compartment, a secondary refrigerant circuit having an evaporating portion located outside of and in contact with the outer wall surface of said .liner and having a condensing portion in ther/mal exchange relationship with one of said primary evaporating means with a refrigerant connection between said evaporating and condensing portions, and an open substantially unrestricted connection connecting the outlet of said freezing evaporating means and the inlet of said food compartment evaporating means.

SY'LVES'IER M. SCHWELLER.

References Cited in the file of this patent UNITED STATES PATENTS 

